How to trigger an approval workflow with a Merge import

Summary:

How can we trigger an approval workflow with the import request created from a Merge import?

Content (required):

We would like for the request created by a Merge import to not immediately commit to the hierarchy of a Planning application, but instead kick off an approval workflow. We have tried every permutation of approval settings we can think of to trigger this, but none of them seem to force an approval workflow to take place, instead resulting in the request created by the import to be committed immediately.

The workaround we have considered here is to create a duplicate Planning application and use the import there, and then have our actual application simply subscribe to the viewpoint that was updated by the import request. Is there another way to achieve this without requiring the creation of a duplicate application?